Janthina janthina is a purple snail species found worldwide in the warm waters of tropical and temperate seas, floating at the surface. These snail excretes mucus from their foot and uses the raft of bubbles to float from place to place. They are often found in large groups and sometimes become stranded on beaches when they are blown ashore by strong winds.
The snail’s shell is reverse counter shaded because of its upside-down position in the water column. There is a light purple shade on the spire of the shell, and a darker purple on the ventral side.
The animal inside the violet shell has a large head on a very flexible neck. The eyes are small and are situated at the base of its tentacles. Common purple snails are blind, but apparently able to locate their prey by smell. They search for food in the form of jellyfish prey like the Portuguese Man O’ War. As they are floating along the pick up barnacles which attach to their shells as hitchhikers as seen in the photo below.